Sample session:

>>> import libvirt
>>> c = libvirt.open('qemu:///session')

>>> c.listSecrets()
['12247729-47d2-a783-88ce-b329d4781cd3', 'reee', 'abc']

>>> s = c.secretDefineXML("<secret ephemeral='no' private='no'>\n<description>Something for use</description>\n<volume>/foo/bar</volume>\n</secret>\n")

>>> s.UUIDString()
'340c2dfb-811b-eda8-da9e-25ccd7bfd650'

>>> s.XMLDesc()
"<secret ephemeral='no' private='no'>\n  <uuid>340c2dfb-811b-eda8-da9e-25ccd7bfd650</uuid>\n  <description>Something for use</description>\n  <volume>/foo/bar</volume>\n</secret>\n"

>>> s.setValue('abc\0xx\xffx')
0

>>> s.value()
'abc\x00xx\xffx'

>>> s.undefine()
0

* python/generator.py: Add rules for virSecret APIs
* python/libvir.c, python/libvirt-python-api.xml: Manual impl of
  virSecretSetValue, virSecretGetValue$ and virConnectListSecrets APIs
* python/libvirt_wrap.h, python/types.c: Wrapper for virSecret objects
* docs/libvirt-api.xml, docs/libvirt-refs.xml,
  docs/html/libvirt-virterror.html, docs/html/libvirt-libvirt.html,
  docs/devhelp/libvirt-virterror.html, docs/devhelp/libvirt-libvirt.html:
  Re-generate with 'make api'